18.33 The investigation has swollen to 40 police officers and another 40 trained mountain rescue personnel, according to Sup Ian John. Police are thought to have accepted a large contingent of 200 volunteers today, sorted into small search groups of 20. A further 200 were also waiting at Machynlleth leisure centre ready to start a fresh shift later in the evening.

18.23 Police have confirmed that they are looking at possible links between April's abduction and a separate incident last week, when a vehicle was seen "acting suspiciously" in the Aberystwyth area.

Sup Ian John said it was too early to say whether any such links existed and whether the earlier report was an attempted abduction.

18.07 A road has been closed off and a woman in tears was seen being driven through the police cordon, believed to be a relative of April Jones, BBC News reports.

17.58 Coastguards have been brought in to help with the search of waterways of the river Dyfi, BBC News reports.

17.55 A man arrested in connection with the abduction of April Jones was known to the five-year-old's family, it has emerged. Press Association is reporting that the man, who was not a relation, was arrested by a police patrol to the north of Machynlleth at around 3.30pm.

17.39 Sky News is reporting that an intensive search is underway along the closed section of road north of Machynlleth by the A487. It reports that the road is closed in both directions. A police helicopter is also in attendance.

17.29 Our graphics team have produced this interactive showing the Jones family home and the place that April was seen playing before she was driven away:

17.20 DS Reg Bevan also credited the public with advancing the investigation. He told the BBC:

I can't underestimate the importance of the public support. The many people who've assisted us in the searching, but also the public, have come forward and provided us with the information and it's as a result of a combination of all that that we've come to this juncture in this investigation."

17.13 DS Reg Bevan has told the BBC that more information on the arrested man may become available once he has been interviewed, which will take place immediately.

Huw Edwards also asked whether the arrested man has any connection to the family. He said:

It's very early stages at this stage. He's clearly a local man; it's a small community. I wouldn't like to speculate further but I may have some more information for you later on."

17.03 SupIan John, also speaking at the conference, paid tribute to the local community, British Transport Police, officers from surrounding forces and offers of support from forces around the UK, including the Metropolitan Police, saying it was "the police family really pulling together to try and find April".

17.02 Police are continuing to pursue all lines of inquiry with a view that April is still alive, Det Sup Reg Bevan also said.

16.57 Police had been "actively looking" for the man, who was arrested while on foot on the side of the road just north of Machynlleth, Det Sup Bevan told Sky News. The arrested man is local and was one of a series of inquiry lines, in part because he had a similar vehicle to the one described, which has been recovered.

16.52 A long stretch of road has been closed in North Wales, and enquiries are being referred to Dyfed Powys police, prompting speculation that the closure is linked to the investigation.

16.48 A 46-year-old man has been arrested. Det Sup Reg Bevan said:

Within the last hour we have arrested a 46-year-old male from the Machynlleth area detained at Aberystwyth police station. We made the arrest just oustside Machynlleth and we hope he'll asist us in locating April who is still missing."

16.33 The family of April Jones are expected at the press conference very shortly. The police are also expected to provide an update on the search.

16.10 Family friend Alan Hughes spoke to mother Coral, 40, in the early hours of this morning. He told BBC News:

I last spoke to Coral last night at 2 o'clock and as you can imagine she was in bits.

"She went back to the house with police and liaison officers."

15.58 April Jones's family will be present at the 4.30pm news conference, it has just been confirmed.

15.37 Some more details on the quiet former council estate of Bryn-y-Gog have come through from reporters at Press Association.

The estate is surrounded on three sides by tree-covered hills and at the centre of it is a series of open greens used by local children. Unattended bicycles and balls frequently litter the grass areas, considered safe from thieves on the close-knit estate.

Matthew Harris, 22, who lives on the estate, said:

The general feeling is one of disbelief, nobody can take it on board.

"I was born and grew up on this estate and remember what it was like as a kid. Everyone played with everyone else.

"It's the same today. Kids play out together and everyone looks after everyone else. Somebody said that this estate once won an award as the safest in Powys.

"I can believe that. Every new family that comes to live here says what a great place it is to bring up kids. They can run free outside, riding bikes or playing football, without any trouble.

"What happened last night is unbelievable. Paul and Coral are loving parents and everyone is devastated for them."

15.19 Det Sup Reg Bevan is due to make another appeal for the whereabouts of April Jones at a press conference at 4.30pm, we've just been informed.

"There's a lot of us here and we want to just do what we can to help and support," one female volunteer said.

"The terrain is very difficult, there is acres and acres of forest, we've all got a bit of local knowledge but I don't know how good that's going to be.

"It feels like a needle in a haystack at times," another volunteer said.

14.58 April Jones's face will appear on digital billboards across the UK from today, charity Missing People have said. Chief executive Martin Houghton-Brown said:

Whilst abduction is very rare, when it happens, everyone must work together – the police, charities and the media. This digital billboard campaign is just one strand of that partnership. We sincerely hope that April is found safe and well very soon.”

14.44 We now have video of the police press conference from a few hours ago, in which the police reveal that April Jones went without a struggle into the vehicle from the driver's side:

14.28 Experts from the UK's child protection centre have been drafted in to help assist with the search. Charlie Hedges, manager for missing, abducted and kidnapped children at the Child Exploitation and Online Protection Centre (Ceop), said he was called at 11pm yesterday and worked on the case through the night. He said:

When the job first came in it was limited information about a five-year-old girl."

"There are the challenges of how you interview a child to get the right information, and with the time of day. You can't interview them through the night."

14.16 Businessesare starting to offer support as the hunt for April intensifies. Mountain Warehouse in Aberystwyth is accepting donations and will be taking torches and waterproofs to Machynlleth to help searchers, Welsh journalist Steffan Rhys reports:

14.09 Here's a map of Machynlleth, showing the Bryn-y-Gog estate where April was abducted and the Bro Dyfi leisure centre where the search is being coordinated:

14.00 April's parents Coral, 40, and Paul, 43, are said to be "besides themselves with worry". A neighbour told a Welsh news agency:

She is the apple of her parent's eyes - in Welsh we call her cariad bach, a little darling.

"They are a lovely people who dote on April."

13.40 The search for April Jones has spread like wildfire across social networks as thousands of people update their statuses to spread the word. More than 3000 people have joined a Facebook group to help find April Jones, while on Twitter it has become the top trending topic:

&lt;noframe&gt;Twitter: sara cox - Lets &lt;a href="http://search.twitter.com/search?q=FindAprilJones" target="_blank"&gt;#FindAprilJones&lt;/a&gt;, thoughts with her mum &amp;amp; dad. Every parents worst nightmare. Just gave my kids an extra long hug at school gates.&lt;/noframe&gt;

13.23 British Transport Police have mobilised volunteers to search for April Jones. The force have assembled groups of 15-20 accompanied by a special officer to do clockwise and anticlockwise searches around Machynlleth. Specialist teams will be scouring the built-up areas.

Volunteers have been told not to touch any clothing they find so as not to contaminate any forensic evidence.

13.16 April Jones had enjoyed a friend's birthday party less than 48 hours before she was abducted, it's been reported on the wires. Family friend Phil, a local businessman, said:

I've got two little girls and they were both at a birthday party with April at the weekend. My youngest is in the same class at school. Where she lives is where all the children play together. It's a safe environment, all the properties look on to where the children play. It's the sort of area where you drop your children off at school and everyone lingers and chats.

"They are a normal family, lovely people. Her dad used to own a hardware shop in the town but that was a few years ago."

12.55 Superintendent Ian John has just spoken to BBC News to give a little detail on the police operation that is underway, which includes "A specialist mountain rescue team, police trained searchers and police dogs."

12.46 Some locals have speculated that an "outsider" is reponsible for the abduction. Shop owner Jacqueline Parsons, 53, said:

I cannot imagine that anyone local is responsible for this. I would be amazed if it turned out to be anyone local. Everyone knows everyone here. You walk down the street and even if you don't know someone's name you speak to them. Everyone is friendly."

"I have never known there to be any crime. People leave their backdoors open when they go out. It's that kind of place.

12.40 Police have been conducting a series of "delicate" and "time-consuming" interviews with children. Det Sup Reg Bevan said:

We have to be mindful of the impact they have on those children but they have been providing us with vital inforatmion."

12.35 Some more snippets from the press conference: April was last seen at "around 7pm" yesterday evening when she was in the company of friends. At least one individual was with her when the abduction took place. Superintendent Reg Bevan said of the vehicle:

The colour hasn't changed - it is described as grey but officers are mindful that it was dusk and there was street lighting on."

12.20 We have video of residents of the tight-knit community speaking about the search for April Jones:

12.17 Police have said that there was no struggle when April went into the vehicle. Detective Superintendent Reg Bevan said:

The indications are that she got into the vehicle willingly."

He added that they have obtained "a very early initial description" of the abductor, but are "not really comfortable" to release that at this stage.

12.12 Detective Superintendent Reg Bevan has commented on the family. He said:

The family as you would imagine are … it must be their worst nightmare. it’s a very, very difficult time for them."

12.09 The press conference has begun. Police have released some more information about the grey vehicle and revealed that April went into the vehicle on the driver's side. Detective Superintendent Reg Bevan said:

It was a small van small on the front and large on the back so that could be interpreted as something similar to a Ford Connect or something like a Land Rover.

"April got in on the driver's side so it might be a left hand drive vehicle."

11.56 Some more background on Machynlleth: it's a town of about 2000 people, about 10 miles inland from the western edge of Wales and the most attractive stretches of coastline in Britain. It's been described as a hub for lovers of the great outdoors.

11.48 Shadow Welsh secretary Owen Smith has offered his support at the Labour Party conference in Manchester:

I am sure I speak for everyone here today and everyone in Wales in saying that our thoughts and our prayers are with April Jones and her family in Machynlleth - the little girl who has gone missing.

"We all hope and pray that she is back in her community and with her family as soon as is humanly possible."

11.46 MachynllethCouncillor Gareth Jones has just been speaking to the BBC. He described the family as "well regarded" and said:

It is very encouraging that people have come forward in such great numbers to help.

"It's the worry and the uncertainty of exactly what has happened and what is to happen next.

"We live in hope and we'll certainly carry on helping the police as much as we can, and of course I need to appeal to people out there who may have some information that maybe they thought was not really of any significance.

"Our thoughts are very much with April and with the family and we'll keep on trying our best."

11.39 Volunteers continued the search for April Jones until around midnight last night, starting again as soon as there was enough light. Dozens of local residents are currently assembled around Machynlleth's leisure centre to offer their help - many of them there since three or four this morning, it has been reported.

11.31 Welsh journalist Steffan Rhys has tweeted a picture of April Jones in the coat she was wearing last night when she was abducted:

11.25 It's understood that Dyfed Powys Police are expected to launch an appeal for the whereabouts of April Jones at a press conference in the next 20 minutes.

11.20 April Jones is now trending on Twitter

11.15 There has been a surge of support on Twitter and Facebook this morning in the search for April Jones. Philip Schofield was one of the first influential Twitter users to write to almost 1.9m followers:

&lt;noframe&gt;Twitter: Phillip Schofield - Please RT If you have any information on missing 5 year old April Jones a hotline number has been released 0300 2000 333&lt;/noframe&gt;

That appeal has been retweeted more than 4000 times, and other influential people have offered their support: